U.S. patent application number 17/394224 was filed with the patent office on 2022-02-10 for graphite foil as an active heating and passive cooling material in a battery pack.
This patent application is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS LLC. The applicant listed for this patent is GM GLOBAL TECHNOLOGY OPERATIONS LLC. Invention is credited to Saad HASAN, Dewen KONG, Haijing LIU, Dave G. RICH, Lyall K. WINGER.
Application Number | 20220045379 17/394224 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-10 |
United States Patent
Application |
20220045379 |
Kind Code |
A1 |
RICH; Dave G. ; et
al. |
February 10, 2022 |
GRAPHITE FOIL AS AN ACTIVE HEATING AND PASSIVE COOLING MATERIAL IN
A BATTERY PACK
Abstract
The present disclosure relates a temperature regulating system
including an anisotropic material for use as a heating material or
element (e.g., an active heater) and a cooling material or element
(e.g., passive cooling) in a battery pack including one or more
electrochemical cells. The temperature regulating system includes
one or more temperature control elements. Each temperature control
element is configured to be in a heat transfer relationship with
one or more electrochemical cells so as to heat and/or cool the one
or more electrochemical cells of the battery pack. Each temperature
control element includes two or more structural elements and one or
more anisotropic elements disposed between the two or more
structural elements. The temperature control elements may be
disposed between the electrochemical cells of the stack, disposed
around the electrochemical cells of the stack, or both.
Inventors: |
RICH; Dave G.; (Sterling
Heights, MI) ; HASAN; Saad; (Detroit, MI) ;
WINGER; Lyall K.; (Waterloo, CA) ; KONG; Dewen;
(Shanghai, CN) ; LIU; Haijing; (Shanghai,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM GLOBAL TECHNOLOGY OPERATIONS LLC |
Detroit |
MI |
US |
|
|
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS
LLC
Detroit
MI
|
Appl. No.: |
17/394224 |
Filed: |
August 4, 2021 |
International
Class: |
H01M 10/615 20060101
H01M010/615; H01M 10/613 20060101 H01M010/613; H01M 10/0525
20060101 H01M010/0525; C09K 5/14 20060101 C09K005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 7, 2020 |
CN |
202010790067.5 |
Claims
1. A temperature control element for an electrochemical cell
comprising: two or more structural elements; and one or more
anisotropic elements disposed between the two or more structural
elements, wherein the one or more anisotropic elements each
comprises one or more anisotropic materials selected from the group
consisting of: graphite, graphene, carbon nanotubes (CNT), crystal
materials, cohesive powder, and combinations thereof, wherein the
temperature control element is configured to be in a heat transfer
relationship with the electrochemical cell so as to heat and/or
cool the electrochemical cell.
2. The temperature control element of claim 1, wherein the
temperature control element further comprises one or more tabs in
electrical communication with the one or more anisotropic elements,
wherein the one or more tabs each comprises one or more of copper,
aluminum, nickel, nickel coated copper, stainless steel, and
aluminum alloys.
3. The temperature control element of claim 2, wherein the one or
more tabs define one or more tab layers, wherein a first tab layer
is disposed between the one or more anisotropic elements and a
first structural element of the two or more structural elements and
a second tab layer is disposed between the one or more anisotropic
elements and a second structural element of the two or more
structural elements, and wherein each tab layer of the one or more
tab layers comprises a first part that is disposed at a first
terminal end and a second part that is disposed at a second
terminal end separated from the first terminal end such that a gap
is defined in a central region between the first part and the
second part of each tab layer of the one or more tab layers.
4. The temperature control element of claim 2, wherein the one or
more anisotropic elements and the one or more tabs define a heating
element.
5. The temperature control element of claim 1, wherein the two or
more structural elements each comprise one or more of mica,
asbestos, marble, porcelain, glass, shellac, resin, rubber, cotton
yarn, paper, linen, rayon, and plastic.
6. The temperature control element of claim 5, wherein at least one
of the two or more structural elements further comprises one or
more adhesive materials selected from the group consisting of:
polyethylene terephthalate (PET), polypropylene (PP), polyethylene
(PE), polytetrafluoroethylene (PTFE), and combinations thereof.
7. The temperature control element of claim 1, wherein the two or
more structural elements are first structural elements and the
temperature control element further comprises one or more second
structural elements disposed between adjacent anisotropic
elements.
8. The temperature control element of claim 1, wherein the one or
more anisotropic elements define one or more foils, wherein each
foil has a thickness greater than or equal to about 1 .mu.m to less
than or equal to about 10,000 .mu.m.
9. The temperature control element of claim 8, wherein the
temperature control element further comprises one or more
insulating materials, the one or more foils each have a plurality
of folds, and the one or more insulating materials are disposed
between the folds of the one or more foils defining the one or more
anisotropic elements.
10. The temperature control element of claim 1, wherein the one or
more anisotropic elements comprise a first grouping of anisotropic
elements comprising one or more first anisotropic materials and a
second grouping of anisotropic elements comprising one or more
second anisotropic materials, wherein each of the first and second
groupings of anisotropic elements are independently controlled.
11. The temperature control element of claim 10, wherein the two or
more structural elements are one or more first structural elements
and the temperature control element further comprises one or more
second structural elements disposed between the first grouping of
anisotropic elements and the second grouping of anisotropic
elements.
12. A battery pack having a temperature regulating system
comprising one or more temperature control elements, wherein the
battery pack comprises: a plurality of electrochemical cells
arranged in a stack, and each temperature control element of the
one or more temperature control elements comprises: two or more
structural elements; and one or more anisotropic elements disposed
between the two or more structural elements, wherein the one or
more anisotropic elements each comprises one or more anisotropic
materials selected from the group consisting of: graphite,
graphene, carbon nanotubes (CNT), crystal materials, cohesive
powder, and combinations thereof, wherein the temperature control
elements are at least one of: (i) disposed between the
electrochemical cells of the stack; (ii) disposed around the
electrochemical cells of the stack; or (iii) both (i) and (ii).
13. The battery pack of claim 12, wherein each of the temperature
control elements further comprises one or more tabs in electrical
communication with the one or more anisotropic elements, wherein
the one or more tabs each comprises one or more of copper,
aluminum, nickel, nickel coated copper, stainless steel, and
aluminum alloys.
14. The battery pack of claim 13, wherein the one or more
anisotropic elements and the one or more tabs of each temperature
control element defines a heating element.
15. The battery pack of claim 12, wherein the two or more
structural elements of each temperature control element comprise
one or more of mica, asbestos, marble, porcelain, glass, shellac,
resin, rubber, cotton yarn, paper, linen, rayon, and plastic and
one or more adhesive materials selected from the group consisting
of: polyethylene terephthalate (PET), polypropylene (PP),
polyethylene (PE), polytetrafluoroethylene (PTFE), and combinations
thereof.
16. The battery pack of claim 12, wherein the one or more
anisotropic elements of each temperature control element comprises
a first grouping of anisotropic elements comprising one or more
first anisotropic elements and a second grouping of anisotropic
elements comprising one or more second anisotropic elements,
wherein each of the first and second groupings of anisotropic
elements are independently controlled.
17. The battery pack of claim 12, wherein each temperature control
element of the one or more temperature control elements is
independently controlled.
18. The battery pack of claim 12, wherein the one or more
temperature control elements defines one or more foils, the one or
more foils each have a plurality of folds, and individual
electrochemical cells of the stack are disposed between folds of
the one or more foils defining the one or more temperature control
elements.
19. The battery pack of claim 12, wherein the one or more
temperature control elements define distinct layers and individual
electrochemical cells of the stack are disposed between the
distinct layers.
20. A temperature control element for an electrochemical cell
comprising: two or more structural elements coated, wherein each
structural element is coated with one or more adhesive layers; and
one or more anisotropic elements disposed between the two or more
structural elements, wherein the one or more anisotropic elements
comprise a first grouping of anisotropic elements comprising one or
more first anisotropic materials and a second grouping of
anisotropic elements comprising one or more second anisotropic
materials, wherein the one or more first anisotropic materials and
the one or more second anisotropic materials are each selected from
the group consisting of: graphite, graphene, carbon nanotubes
(CNT), crystal materials, cohesive powder, and combinations
thereof, wherein each of the first and second groupings of
anisotropic elements are independently controlled, and wherein the
temperature control element is configured to be in a heat transfer
relationship with the electrochemical cell so as to heat and/or
cool the electrochemical cell.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit and priority of Chinese
Application No. 202010790067.5, filed Aug. 7, 2020. The entire
disclosure of the above application is incorporated herein by
reference.
INTRODUCTION
[0002] This section provides background information related to the
present disclosure which is not necessarily prior art.
[0003] The present disclosure relates to the use of an anisotropic
material or element, such as graphite, for example in the form of a
foil, as a heating material or element (e.g., an active heater) and
a cooling material or element (e.g., passive cooling), for example
within a battery pack including one or more electrochemical cells,
so as to create controllable temperature regions within the battery
and/or pack (e.g., isotherms and other desired thermal patterns
and/or gradients) that may prevent and/or minimize, for example,
lithium plating, uneven wear and, drying and over-heating, and
improve wide-range temperature performance.
[0004] Electrochemical energy storage devices, such as lithium-ion
batteries, can be used in a variety of products, including
automotive products, such as start-stop systems (e.g., 12V
start-stop systems), battery-assisted systems (".mu.BAS"), Hybrid
Electric Vehicles ("HEVs"), and Electric Vehicles ("EVs"). Typical
lithium-ion batteries include two electrodes, a separator, and an
electrolyte. However, in solid-state or semi-solid state batteries,
the separator and solid-state electrolyte may be a single
component. Lithium-ion batteries may also include various terminal
(e.g., tab) and packaging materials (e.g., pouch). In
electrochemical cells, such as in lithium-ion batteries, one of the
two electrodes serves as a positive electrode or cathode, and the
other electrode serves as a negative electrode or anode.
[0005] Rechargeable lithium-ion batteries operate by reversibly
passing lithium ions back and forth between the negative electrode
and the positive electrode. For example, lithium ions may move from
the positive electrode to the negative electrode during charging of
the battery and in the opposite direction when discharging the
battery. A separator and/or electrolyte may be disposed between the
negative and positive electrodes. The electrolyte is suitable for
conducting lithium ions (or sodium ions in the case of sodium-ion
batteries) between the electrodes and, like the two electrodes, may
be in a solid form, a liquid form, or a solid-liquid hybrid form.
In solid-state batteries, which include a solid-state electrolyte
disposed between solid-state electrodes, the solid-state
electrolyte physically separates the electrodes so that a distinct
separator is not required.
[0006] When operating at elevated temperatures, electrochemical
cells, including batteries, can be subject to capacity loss, power
fade, and in certain circumstances, thermal runaway. On the other
hand, operating at temperatures that are too low may result in
increased resistance, increased plating, and decreased capacity.
Maintaining desired operating temperature ranges maximizes the
efficiency and life span of the cells. However, in certain
instances, for example as a result of current flow paths, common
algorithmic heating solutions tend to preferentially warm areas
around and between battery terminals more quickly than the bottom
and or sides of the battery. Such non-uniform thermal distribution
may potentially cause the cell bottom and sides to be more
susceptible to lithium-plating as the cell warms, as well as to
create weak/strong characteristics at different places within the
battery. Further still, in instances of lithium-ion battery packs,
where batteries or cells are electrically connected (e.g., in
parallel or in series), for example in a stack, so as to increase
overall output, cells located at internal positions within the pack
may experience instances of higher thermal resistance than that of
cells located at external positions. Such temperature differentials
within a pack may result in different cell performance degradation.
Accordingly, mechanisms and materials (e.g., temperature regulation
systems) for electrochemical cells or batteries, and battery packs
including one or more electrically connected batteries or cells,
are desirable.
SUMMARY
[0007] This section provides a general summary of the disclosure,
and is not a comprehensive disclosure of its full scope or all of
its features.
[0008] In various aspects, a temperature control element for an
electrochemical cell is provided. The temperature control element
may include two or more structural elements and one or more
anisotropic elements disposed between the two or more structural
elements. The one or more anisotropic elements may each include one
or more anisotropic materials selected from the group consisting
of: graphite, graphene, carbon nanotubes (CNT), crystal materials,
cohesive powder, and combinations thereof. The temperature control
element may be configured to be in a heat transfer relationship
with the electrochemical cell so as to heat and/or cool the
electrochemical cell.
[0009] In one aspect, the temperature control element may further
include one or more tabs in electrical communication with the one
or more anisotropic elements. The one or more tabs may each include
one or more of copper, aluminum, nickel, nickel coated copper,
stainless steel, and aluminum alloys.
[0010] In one aspect, the one or more tabs may define one or more
tab layers. For example, a first tab layer may be disposed between
the one or more anisotropic elements and a first structural element
of the two or more structural elements, and a second tab layer may
be disposed between the one or more anisotropic elements and a
second structural element of the two or more structural elements.
Each tab layer of the one or more tab layers may include a first
part that is disposed at a first terminal end and a second part
that is disposed at a second terminal end separated from the first
terminal end such that a gap may be defined in a central region
between the first part and the second part of each tab layer of the
one or more tab layers.
[0011] In one aspect, the one or more anisotropic elements and the
one or more tabs may define a heating element.
[0012] In one aspect, the two or more structural elements may each
include one or more of mica, asbestos, marble, porcelain, glass,
shellac, resin, rubber, cotton yarn, paper, linen, rayon, and
plastic.
[0013] In one aspect, at least one of the two or more structural
elements may further include one or more adhesive materials that
may be selected from the group consisting of: polyethylene
terephthalate (PET), polypropylene (PP), polyethylene (PE),
polytetrafluoroethylene (PTFE), and combinations thereof.
[0014] In one aspect, the two or more structural elements may be
first structural elements and the temperature control element may
further include one or more second structural elements disposed
between adjacent anisotropic elements.
[0015] In one aspect, the one or more anisotropic elements may
define one or more foils. Each foil may have a thickness greater
than or equal to about 1 .mu.m to less than or equal to about
10,000 .mu.m.
[0016] In one aspect, the temperature control element may further
include one or more insulating materials, the one or more foils may
each have a plurality of folds, and the one or more insulating
materials may be disposed between folds of the one or more foils
defining the one or more anisotropic elements.
[0017] In one aspect, the one or more anisotropic elements includes
a first grouping of anisotropic elements including one or more
first anisotropic materials and a second grouping of anisotropic
elements including one or more second anisotropic materials. Each
of the first and second groupings of anisotropic elements may be
independently controlled.
[0018] In one aspect, the two or more structural elements are one
or more first structural elements and the temperature control
element further includes one or more second structural elements
disposed between the first grouping of anisotropic elements and the
second grouping of anisotropic elements.
[0019] In various aspects, the present disclosure provides an
example battery pack having a temperature regulating system
including one or more temperature control elements. The battery
pack includes a plurality of electrochemical cells arranged in a
stack and defining the battery pack. Each temperature control
element of the one or more temperature control elements includes
two or more structural elements and one or more anisotropic
elements disposed between the two or more structural elements. The
one or more anisotropic elements may each include one or more
anisotropic materials selected from the group consisting of:
graphite, graphene, carbon nanotubes (CNT), crystal materials,
cohesive powder, and combinations thereof. The temperature control
elements may be at least one of: (i) disposed between the
electrochemical cells of the stack; (ii) disposed around the
electrochemical cells of the stack; or (iii) both (i) and (ii).
[0020] In one aspect, each of the temperature control elements may
further include one or more tabs in electrical communication with
the one or more anisotropic elements. The one or more tabs may each
include one or more of copper, aluminum, nickel, nickel coated
copper, stainless steel, and aluminum alloys.
[0021] In one aspect, the one or more anisotropic elements and the
one or more tabs of each temperature control element may define a
heating element.
[0022] In one aspect, the two or more structural elements of each
temperature control element may include one or more of mica,
asbestos, marble, porcelain, glass, shellac, resin, rubber, cotton
yarn, paper, linen, rayon, and plastic; and the one or more
adhesive materials may be selected from the group consisting of:
polyethylene terephthalate (PET), polypropylene (PP), polyethylene
(PE), polytetrafluoroethylene (PTFE), and combinations thereof.
[0023] In one aspect, the one or more anisotropic elements of each
temperature control element may include a first grouping of
anisotropic elements that includes one or more first anisotropic
elements and a second grouping of anisotropic elements that
includes one or more second anisotropic elements. Each of the first
and second groupings of anisotropic elements may be independently
controlled.
[0024] In one aspect, each temperature control element of the one
or more temperature control elements may be independently
controlled.
[0025] In one aspect, the one or more temperature control elements
may define one or more foils. The one or more foils may each have a
plurality of folds. Individual electrochemical cells of the stack
may be disposed between folds of the one or more foils so as to
define the one or more temperature control elements.
[0026] In one aspect, the one or more temperature control elements
may define distinct layers and individual electrochemical cells of
the stack may be disposed between the distinct layers.
[0027] In various aspects, a temperature control element for an
electrochemical cell is provided. The temperature control element
includes two or more structural elements coated and one or more
anisotropic elements disposed between the two or more structural
elements. Each structural element may be coated with one or more
adhesive layers. The one or more anisotropic elements may include a
first grouping of anisotropic elements including one or more first
anisotropic materials and a second grouping of anisotropic elements
including one or more second anisotropic materials. The one or more
first anisotropic materials and the one or more second anisotropic
materials may each be selected from the group consisting of:
graphite, graphene, carbon nanotubes (CNT), crystal materials,
cohesive powder, and combinations thereof. Each of the first and
second groupings of anisotropic elements may be independently
controlled. The temperature control element may be configured to be
in a heat transfer relationship with the electrochemical cell so as
to heat and/or cool the electrochemical cell.
[0028] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples
in this summary are intended for purposes of illustration only and
are not intended to limit the scope of the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The drawings described herein are for illustrative purposes
only of selected embodiments and not all possible implementations,
and are not intended to limit the scope of the present
disclosure.
[0030] FIG. 1 is a schematic of an example of an electrochemical
battery cell for cycling lithium ions;
[0031] FIG. 2 is a schematic illustration of an example battery
pack including a plurality of battery modules;
[0032] FIG. 3A is a cross-sectional schematic illustration of an
example temperature control element in accordance with various
aspects of the present disclosure;
[0033] FIG. 3B is a cross-sectional schematic illustration of an
example structural layer having one or more supporting adhesive
coatings;
[0034] FIG. 4 is a cross-sectional schematic illustration of
another example temperature control element in accordance with
various aspects of the present disclosure;
[0035] FIG. 5 is a top-down schematic illustration of another
example temperature control element having different thermal zones
in accordance with various aspects of the present disclosure;
[0036] FIG. 6 is a cross-sectional schematic illustration of an
example battery pack including a plurality of battery cells and
temperature control elements in accordance with various aspects of
the present disclosure;
[0037] FIG. 7 is a cross-sectional schematic illustration of
another example battery pack including a plurality of battery cells
and temperature control elements in accordance with various aspects
of the present disclosure;
[0038] FIG. 8A is a cell temperature (.degree. C.) profile for a
conventional electrochemical cell over a sixty-minute period;
and
[0039] FIG. 8B is a cell temperature (.degree. C.) profile for an
electrochemical cell including temperature control elements in
accordance with various aspects of the present disclosure.
[0040] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION
[0041] Example embodiments are provided so that this disclosure
will be thorough, and will fully convey the scope to those who are
skilled in the art. Numerous specific details are set forth such as
examples of specific compositions, components, devices, and
methods, to provide a thorough understanding of embodiments of the
present disclosure. It will be apparent to those skilled in the art
that specific details need not be employed, that example
embodiments may be embodied in many different forms and that
neither should be construed to limit the scope of the disclosure.
In some example embodiments, well-known processes, well-known
device structures, and well-known technologies are not described in
detail.
[0042] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be
limiting. As used herein, the singular forms "a," "an," and "the"
may be intended to include the plural forms as well, unless the
context clearly indicates otherwise. The terms "comprises,"
"comprising," "including," and "having," are inclusive and
therefore specify the presence of stated features, elements,
compositions, steps, integers, operations, and/or components, but
do not preclude the presence or addition of one or more other
features, integers, steps, operations, elements, components, and/or
groups thereof. Although the open-ended term "comprising," is to be
understood as a non-restrictive term used to describe and claim
various embodiments set forth herein, in certain aspects, the term
may alternatively be understood to instead be a more limiting and
restrictive term, such as "consisting of" or "consisting
essentially of." Thus, for any given embodiment reciting
compositions, materials, components, elements, features, integers,
operations, and/or process steps, the present disclosure also
specifically includes embodiments consisting of, or consisting
essentially of, such recited compositions, materials, components,
elements, features, integers, operations, and/or process steps. In
the case of "consisting of," the alternative embodiment excludes
any additional compositions, materials, components, elements,
features, integers, operations, and/or process steps, while in the
case of "consisting essentially of," any additional compositions,
materials, components, elements, features, integers, operations,
and/or process steps that materially affect the basic and novel
characteristics are excluded from such an embodiment, but any
compositions, materials, components, elements, features, integers,
operations, and/or process steps that do not materially affect the
basic and novel characteristics can be included in the
embodiment.
[0043] Any method steps, processes, and operations described herein
are not to be construed as necessarily requiring their performance
in the particular order discussed or illustrated, unless
specifically identified as an order of performance. It is also to
be understood that additional or alternative steps may be employed,
unless otherwise indicated.
[0044] When a component, element, or layer is referred to as being
"on," "engaged to," "connected to," or "coupled to" another element
or layer, it may be directly on, engaged, connected or coupled to
the other component, element, or layer, or intervening elements or
layers may be present. In contrast, when an element is referred to
as being "directly on," "directly engaged to," "directly connected
to," or "directly coupled to" another element or layer, there may
be no intervening elements or layers present. Other words used to
describe the relationship between elements should be interpreted in
a like fashion (e.g., "between" versus "directly between,"
"adjacent" versus "directly adjacent," etc.). As used herein, the
term "and/or" includes any and all combinations of one or more of
the associated listed items.
[0045] Although the terms first, second, third, etc. may be used
herein to describe various steps, elements, components, regions,
layers and/or sections, these steps, elements, components, regions,
layers and/or sections should not be limited by these terms, unless
otherwise indicated. These terms may be only used to distinguish
one step, element, component, region, layer or section from another
step, element, component, region, layer or section. Terms such as
"first," "second," and other numerical terms when used herein do
not imply a sequence or order unless clearly indicated by the
context. Thus, a first step, element, component, region, layer or
section discussed below could be termed a second step, element,
component, region, layer or section without departing from the
teachings of the example embodiments.
[0046] Spatially or temporally relative terms, such as "before,"
"after," "inner," "outer," "beneath," "below," "lower," "above,"
"upper," and the like, may be used herein for ease of description
to describe one element or feature's relationship to another
element(s) or feature(s) as illustrated in the figures. Spatially
or temporally relative terms may be intended to encompass different
orientations of the device or system in use or operation in
addition to the orientation depicted in the figures.
[0047] Throughout this disclosure, the numerical values represent
approximate measures or limits to ranges to encompass minor
deviations from the given values and embodiments having about the
value mentioned as well as those having exactly the value
mentioned. Other than in the working examples provided at the end
of the detailed description, all numerical values of parameters
(e.g., of quantities or conditions) in this specification,
including the appended claims, are to be understood as being
modified in all instances by the term "about" whether or not
"about" actually appears before the numerical value. "About"
indicates that the stated numerical value allows some slight
imprecision (with some approach to exactness in the value;
approximately or reasonably close to the value; nearly). If the
imprecision provided by "about" is not otherwise understood in the
art with this ordinary meaning, then "about" as used herein
indicates at least variations that may arise from ordinary methods
of measuring and using such parameters. For example, "about" may
comprise a variation of less than or equal to 5%, optionally less
than or equal to 4%, optionally less than or equal to 3%,
optionally less than or equal to 2%, optionally less than or equal
to 1%, optionally less than or equal to 0.5%, and in certain
aspects, optionally less than or equal to 0.1%.
[0048] In addition, disclosure of ranges includes disclosure of all
values and further divided ranges within the entire range,
including endpoints and sub-ranges given for the ranges.
[0049] Example embodiments will now be described more fully with
reference to the accompanying drawings.
[0050] Electrochemical cells or batteries employable, for example,
in vehicles, such as automobiles, motorcycles, boats, tractors,
buses, mobile homes, campers, all-terrain vehicles, snowmobiles,
airplanes, and tanks, may be exposed to wide operating
temperatures, for example temperatures in a range of greater than
or equal to about -20.degree. C. to less than or equal to about
60.degree. C. Accordingly, the current technology provides systems
and methods for regulating the operating temperature of
electrochemical cells or batteries, and battery packs including one
or more electrically connected (e.g., in series or parallel)
electrochemical cells or batteries. More particularly, the current
technology, as further detailed below, relates to the use of an
anisotropic material or element, such as graphite, for example in
the form of a foil, as a heating material or element (e.g., an
active heater) and a cooling material or element (e.g., passive
cooling), so as to create controllable temperature regions within
the battery and/or pack (e.g., isotherms and other desired thermal
patterns and/or gradients) that may prevent, for example, lithium
plating, and improve temperature performance over a wide range of
temperatures.
[0051] By way of non-limiting background, an exemplary schematic
illustration of an electrochemical cell or battery 20 (also
referred to as the battery, which comprises at least one
electrochemical cell) that cycles ions is shown in FIG. 1. Unless
specifically indicated otherwise, the term "ions" as used herein
refers to lithium ions or sodium ions. For example, an
electrochemical cell that cycles sodium ions has similar components
as the battery 20 that cycles lithium ions, but replaces the
lithium and lithium ions with sodium and sodium ions in
corresponding components.
[0052] The battery 20 includes a negative electrode (i.e., an
anode) 22, a positive electrode (i.e., a cathode) 24, and a
separator 26 (e.g., a microporous polymeric separator) disposed
between the two electrodes 22, 24. An electrolyte 30 is present
throughout the separator 26 and, optionally, in the negative
electrode 22 and positive electrode 24. A negative electrode
current collector 32 may be positioned at or near the negative
electrode 22 and a positive electrode current collector 34 may be
positioned at or near the positive electrode 24. While not shown,
the negative electrode current collector 32 and the positive
electrode current collector 34 may be coated on one or both sides,
as is known in the art. In certain aspects, the current collectors
32, 34 may be coated with an electrode active material/electrode
layer on both sides. The negative electrode current collector 32
and positive electrode current collector 34 respectively collect
and move free electrons to and from an external circuit 40 (as
shown by the block arrows). For example, an interruptible external
circuit 40 and a load device 42 may connect the negative electrode
22 (through the negative electrode current collector 32) and the
positive electrode 24 (through the positive electrode current
collector 34). In this manner, current collectors 32, 34 may define
tabs (not shown) that are in electrical communication with battery
terminals (not shown).
[0053] The battery 20 can generate an electric current during
discharge by way of reversible electrochemical reactions that occur
when the external circuit 40 is closed (to connect the negative
electrode 22 and the positive electrode 24) and the negative
electrode 22 contains a relatively greater quantity of lithium than
the positive electrode 24. The chemical potential difference
between the positive electrode 24 and the negative electrode 22
drives electrons produced by a reaction, for example, the oxidation
of intercalated lithium, at the negative electrode 22 through the
external circuit 40 towards the positive electrode 24. Lithium ions
that are also produced at the negative electrode 22 are
concurrently transferred through the electrolyte 30 contained in
the separator 26 towards the positive electrode 24. The electrons
flow through the external circuit 40 and the lithium ions migrate
across the separator 26 containing the electrolyte solution 30 to
form intercalated lithium at the positive electrode 24. As noted
above, electrolyte 30 is typically also present in the negative
electrode 22 and positive electrode 24. The electric current
passing through the external circuit 40 can be harnessed and
directed through the load device 42 until the lithium in the
negative electrode 22 is depleted and the capacity of the battery
20 is diminished.
[0054] While the load device 42 may be any number of known
electrically powered devices, a few specific examples of
power-consuming load devices include an electric motor for a hybrid
vehicle or an all-electric vehicle, a laptop computer, a tablet
computer, a cellular phone, and cordless power tools or appliances,
by way of non-limiting example. The load device 42 may also be a
power-generating apparatus that charges the lithium-ion battery 20
for purposes of storing energy. In certain other variations, the
electrochemical cell may be a supercapacitor, such as a lithium-ion
based supercapacitor.
[0055] The battery 20 can be charged or re-energized at any time by
connecting an external power source to the lithium ion battery 20
to reverse the electrochemical reactions that occur during battery
discharge. Connecting an external electrical energy source to the
battery 20 promotes a reaction, for example, non-spontaneous
oxidation of intercalated lithium, at the positive electrode 24 so
that electrons and lithium ions are produced. The lithium ions flow
back towards the negative electrode 22 through the electrolyte 30
across the separator 26 to replenish the negative electrode 22 with
lithium (e.g., intercalated lithium) for use during the next
battery discharge event. As such, a complete discharging event
followed by a complete charging event is considered a cycle, where
lithium ions are cycled between the positive electrode 24 and the
negative electrode 22. The external power source that may be used
to charge the battery 20 may vary depending on the size,
construction, and particular end-use of the battery 20. Some
notable and exemplary external power sources include, but are not
limited to, an AC-DC converter connected to an AC electrical power
grid though a wall outlet and a motor vehicle alternator.
Accordingly, the lithium-ion battery 20 can generate electric
current for the load device 42 that can be operatively connected to
the external circuit 40.
[0056] In many lithium ion battery configurations, each of the
negative electrode current collector 32, negative electrode 22, the
separator 26, positive electrode 24, and positive electrode current
collector 34 are prepared as relatively thin layers (for example,
from several microns to a fraction of a millimeter or less in
thickness) that define a respective cell, which are then assembled
in layers connected in electrical parallel arrangement to provide a
suitable electrical energy and power package. Further, the
separator 26 operates as an electrical insulator by being
sandwiched between the negative electrode 22 and the positive
electrode 24 to prevent physical contact and thus, the occurrence
of a short circuit. Where the electrolyte 30 is a liquid or
semi-solid, the separator 26, in addition to providing a physical
barrier between the two electrodes 22, 24, is porous and thus acts
like a sponge that contains the electrolyte 30 in a network of open
pores during the cycling of lithium ions, to facilitate functioning
of the battery 20.
[0057] The battery 20 can include a variety of other components
that while not depicted here are nonetheless known to those of
skill in the art. For instance, the battery 20 may include a
casing, gaskets, terminal caps, tabs, battery terminals, and any
other conventional components or materials that may be situated
within the battery 20, including between or around the negative
electrode 22, the positive electrode 24, and/or the separator 26.
As noted above, the size and shape of the battery 20 may vary
depending on the particular application for which it is designed.
Battery-powered vehicles and hand-held consumer electronic devices,
for example, are two examples where the battery 20 would most
likely be designed to different size, capacity, and power-output
specifications.
[0058] In various aspects, the battery 20 may also be connected,
for example in a stack, with series or parallel electrical
connections, with other similar lithium ion cells or batteries to
produce a greater voltage output, energy, and power if it is
required by the load device 42. For example, a plurality of cells
or batteries 20 may be stacked to define a battery module 50 and a
plurality of battery modules 50 may be operatively-connected in
series or parallel to define a battery pack 100, as illustrated in
FIG. 2. As the skilled artisan will appreciate, each battery module
50 may include one or more cells or batteries 20 (as illustrated in
FIG. 1), and the battery pack 100 may include two or more battery
modules 50. For example, as illustrated in FIG. 2, the battery pack
100 may include two or more battery modules 50. In FIG. 2, the
central battery module 50 is shown with dashed lines and is meant
to illustrate that the central battery module 50 is optional or can
be any number of other battery modules 50, such as, for example
only, greater than or equal to 1 to less than or equal to less than
or equal to about 50 battery modules 50.
[0059] The battery pack 100 comprises a first side surface 70
defined by a first cell wall 54 of a first terminal battery module
50 of the plurality, an opposing second side surface 72 defined by
a second cell wall 56 of a last terminal battery module 50 of the
plurality, and opposing first and second stack edges 74, 76 defined
by the first and second cell edges 58, 60 of each battery module 50
of the plurality. The first and second stack edges 74, 76 are
orthogonal to the first and second side surfaces 70, 72. The
battery pack 100 also comprises opposing first and second stack
ends 78, 80 defined by the first and second cell ends 62, 64 of
each battery module 50 of the plurality. Each battery module 50 may
include tabs 66 extending generally outwardly from at least one of
the first and second cell ends 62, 64 of each battery module 50 of
the plurality. In certain aspects, each battery module 50 includes
two tabs 66, one being associated with at least one anode 22 and
the other tab 66 being associated with at least one cathode 24. The
two tabs 66 can be located on opposing cell ends 62, 64 of each
battery module 50 of the plurality. In other instances, the two
tabs can both be located on a single end, the single end being
either the first cell end 62 or the second cell end 64 of the
respective battery module 50. Although the tabs 66 of each battery
20 are shown exposed in FIG. 2, it is understood that they can be
connected, such as with a bus bar as a non-limiting example.
[0060] With renewed reference to FIG. 1, the positive electrode 24,
the negative electrode 22, and the separator 26 may each include an
electrolyte solution or system 30 inside their pores, capable of
conducting lithium ions between the negative electrode 22 and the
positive electrode 24. Any appropriate electrolyte 30, whether in
solid, liquid, or gel form, capable of conducting lithium ions
between the negative electrode 22 and the positive electrode 24 may
be used in the lithium-ion battery 20. In certain aspects, the
electrolyte 30 may be a non-aqueous liquid electrolyte solution
that includes a lithium salt dissolved in an organic solvent or a
mixture of organic solvents. Numerous conventional non-aqueous
liquid electrolyte 30 solutions may be employed in the lithium-ion
battery 20.
[0061] A non-limiting list of lithium salts that may be dissolved
in an organic solvent to form the nonaqueous liquid electrolyte
solution includes lithium hexafluorophosphate (LiPF.sub.6), lithium
fluorosulfonylimide (LiN(FSO.sub.2).sub.2) (LiFSI), lithium
perchlorate (LiClO.sub.4), lithium tetrachloroaluminate
(LiAlCl.sub.4), lithium iodide (LiI), lithium bromide (LiBr),
lithium thiocyanate (LiSCN), lithium tetrafluoroborate
(LiBF.sub.4), lithium tetraphenylborate
(LiB(C.sub.6H.sub.5).sub.4), lithium hexafluoroarsenate
(LiAsF.sub.6), lithium trifluoromethanesulfonate
(LiCF.sub.3SO.sub.3), lithium bis(trifluoromethanesulfonimide)
(LiTFSI) (LiN(CF.sub.3SO.sub.2).sub.2), and combinations
thereof.
[0062] These and other similar lithium salts may be dissolved in a
variety of organic solvents, including, but not limited to, various
alkyl carbonates, such as cyclic carbonates (e.g., ethylene
carbonate (EC), propylene carbonate (PC), butylene carbonate (BC),
fluoroethylene carbonate (FEC)), linear carbonates (e.g., dimethyl
carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate
(EMC)), aliphatic carboxylic esters (e.g., methyl formate, methyl
acetate, methyl propionate), .gamma.-lactones (e.g.,
.gamma.-butyrolactone, .gamma.-valerolactone), chain structure
ethers (e.g., 1,2-dimethoxyethane (DME), 1-2-diethoxyethane,
ethoxymethoxyethane), cyclic ethers (e.g., tetrahydrofuran,
2-methyltetrahydrofuran, 1,3-dioxolane (DOL)), sulfur compounds
(e.g., sulfolane), and combinations thereof. In various aspects,
the electrolyte may include greater than or equal to about 0.5 M to
less than or equal to about 4.0 M of the one or more lithium
salts.
[0063] The separator 26 operates as both an electrical insulator
and a mechanical support. In one embodiment, a microporous
polymeric separator 26 comprises a polyolefin. The polyolefin may
be a homopolymer (derived from a single monomer constituent) or a
heteropolymer (derived from more than one monomer constituent),
which may be either linear or branched. If a heteropolymer is
derived from two monomer constituents, the polyolefin may assume
any copolymer chain arrangement, including those of a block
copolymer or a random copolymer. Similarly, if the polyolefin is a
heteropolymer derived from more than two monomer constituents, it
may likewise be a block copolymer or a random copolymer. In certain
aspects, the polyolefin may be polyethylene (PE), polypropylene
(PP), or a blend of PE and PP.
[0064] When the separator 26 is a microporous polymeric separator,
it may be a single layer or a multi-layer laminate, which may be
fabricated from either a dry or wet process. For example, in one
embodiment, a single layer of the polyolefin may form the entire
microporous polymer separator 26. In other aspects, the separator
26 may be a fibrous membrane having an abundance of pores extending
between the opposing surfaces and may have a thickness of less than
a millimeter, for example. As another example, multiple discrete
layers of similar or dissimilar polyolefins may be assembled to
form the microporous polymer separator 26. The polyolefins may be
homopolymers (derived from a single monomer constituent) or
heteropolymers (derived from more than one monomer constituent),
which may be either linear or branched. If a heteropolymer is
derived from two monomer constituents, the polyolefin may assume
any copolymer chain arrangement, including those of a block
copolymer or a random copolymer. Similarly, if the polyolefin is a
heteropolymer derived from more than two monomer constituents, it
may likewise be a block copolymer or a random copolymer. In certain
aspects, the polyolefin may be polyethylene (PE), polypropylene
(PP), a blend of PE and PP, or multi-layered structured porous
films of PE and/or PP. The microporous polymer separator 26 may
also comprise other polymers in addition to the polyolefin, such
as, but not limited to, polyethylene terephthalate (PET),
polyvinylidene fluoride (PVDF), and/or a polyamide. Furthermore,
the porous separator 26 may be mixed with a ceramic material or its
surface may be coated in a ceramic material. For example, a ceramic
coating may include alumina (Al.sub.2O.sub.3), silicon dioxide
(SiO.sub.2), titania (TiO.sub.2), or combinations thereof.
[0065] Commercially available polyolefin porous membranes include
CELGARD.RTM. 2500 (a monolayer polypropylene separator) and
CELGARD.RTM. 2320 (a trilayer
polypropylene/polyethylene/polypropylene separator), both available
from Celgard, LLC. The polyolefin layer and any other optional
polymer layers may further be included in the microporous polymer
separator 26 as a fibrous layer to help provide the microporous
polymer separator 26 with appropriate structural and porosity
characteristics. Various conventionally available polymers and
commercial products for forming the separator 26 are contemplated,
as well as the many manufacturing methods that may be employed to
produce such microporous polymer separators 26.
[0066] In alternative aspects, the porous separator 26 and the
electrolyte 30 may be replaced with a solid-state electrolyte (SSE)
(not shown) that functions as both an electrolyte and a separator,
as are known in the art. The SSE may be disposed between the
positive electrode 24 and negative electrode 22. The SSE
facilitates transfer of lithium ions, while mechanically separating
and providing electrical insulation between the negative and
positive electrodes 22, 24. By way of non-limiting example, SSEs
may include LiTi.sub.2(PO.sub.4).sub.3, LiGe.sub.2(PO.sub.4).sub.3,
Li.sub.7La.sub.3Zr.sub.2O.sub.12, Li.sub.3xLa.sub.2/3-xTiO.sub.3,
Li.sub.3PO.sub.4, Li.sub.3N, Li.sub.4GeS.sub.4,
Li.sub.10GeP.sub.2S.sub.12, Li.sub.2S--P.sub.2S.sub.5,
Li.sub.6PS.sub.5C.sub.1, Li.sub.6PS.sub.5Br, Li.sub.6PS.sub.5I,
Li.sub.3OCl, Li.sub.2.99Ba.sub.0.005ClO,
Li.sub.5La.sub.3M.sub.2O.sub.12, where M is niobium (Nb) or
tantalum (Ta), Li.sub.2O--La.sub.2O.sub.3-M.sub.2O.sub.5, where M
is niobium (Nb) or tantalum (Ta), LiAlTi(PO.sub.4).sub.2, or
LISICON materials like Li.sub.2+2xZn.sub.1-xGeO.sub.4 or
Li.sub.(3+x)Ge.sub.xV.sub.(1-x)O.sub.4, where x may be 0 and 1, and
any combinations thereof by way of example. In certain variations,
the SSE may be selected from the group consisting of:
Li.sub.5La.sub.3M.sub.2O.sub.12, where M is niobium (Nb) or
tantalum (Ta), Li.sub.2O--La.sub.2O.sub.3-M.sub.2O.sub.5, where M
is niobium (Nb) or tantalum (Ta), LiAlTi(PO.sub.4).sub.2, or
LISICON materials like Li.sub.2+2xZn.sub.1-xGeO.sub.4 or
Li.sub.(3+x)Ge.sub.xV.sub.(1-x)O.sub.4, where x may be 0 and 1, and
combinations thereof.
[0067] The negative electrode 22 may be formed from a lithium host
material that is capable of functioning as a negative terminal of a
lithium-ion battery. The negative electrode 22 may thus include the
electrode active material and, optionally, another electrically
conductive material, as well as one or more polymeric binder
materials to structurally hold the lithium host electroactive
material particles together.
[0068] In certain variations, the negative electrode active
material may comprise lithium, such as, for example, lithium metal.
In certain variations, the negative electrode 22 is a film or layer
formed of lithium metal or an alloy of lithium. Other materials can
also be used to form the negative electrode 22, including, for
example, lithium-silicon and silicon containing binary and ternary
alloys and/or tin-containing alloys, such as Si--Sn, SiSnFe,
SiSnAl, SiFeCo, SnO.sub.2, and the like. In certain alternative
embodiments, lithium-titanium anode materials are contemplated,
such as Li.sub.4+xTi.sub.5O.sub.12, where 0.ltoreq.x.ltoreq.3,
including lithium titanate (Li.sub.4Ti.sub.5O.sub.12) (LTO). Thus,
negative electroactive materials for the negative electrode 22 may
be selected from the group consisting of: lithium, graphite,
silicon, silicon-containing alloys, tin-containing alloys, and
combinations thereof.
[0069] Such negative electrode active materials may be optionally
intermingled with an electrically conductive material that provides
an electron conduction path and/or at least one polymeric binder
material that improves the structural integrity of the negative
electrode 22. By way of non-limiting example, the negative
electrode 22 may include an active material including electroactive
material particles (e.g., graphite particles) intermingled with a
polymeric binder material selected from the group consisting of
polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE),
ethylene propylene diene monomer (EPDM) rubber, carboxymethoxyl
cellulose (CMC), nitrile butadiene rubber (NBR), lithium
polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate,
lithium alginate, and combinations thereof, by way of example.
Additional suitable electrically conductive materials may include
carbon-based materials or a conductive polymer. Carbon-based
materials may include, by way of non-limiting example, particles of
KETCHEN.TM. black, DENKA.TM. black, acetylene black, carbon black,
and the like. Conductive metal particles may include nickel, gold,
silver, copper, aluminum, and the like. Examples of a conductive
polymer include polyaniline, polythiophene, polyacetylene,
polypyrrole, and the like. In certain aspects, mixtures of
conductive materials may be used.
[0070] A negative electrode may comprise the negative electrode
active material present at greater than about 60 wt. % of the
overall weight of the electrode, optionally greater than or equal
to about 65 wt. %, optionally greater than or equal to about 70 wt.
%, optionally greater than or equal to about 75 wt. %, optionally
greater than or equal to about 80 wt. %, optionally greater than or
equal to about 85 wt. %, optionally greater than or equal to about
90 wt. %, and in certain variations, optionally greater than or
equal to about 95% of the overall weight of the electrode.
[0071] The binder may be present in the negative electrode 22 at
greater than or equal to about 1 wt. % to less than or equal to
about 20 wt. %, optionally greater than or equal to about 1 wt. %
to less than or equal to about 10 wt. %, optionally greater than or
equal to about 1 wt. % to less than or equal to about 8 wt. %,
optionally greater than or equal to about 1 wt. % to less than or
equal to about 7 wt. %, optionally greater than or equal to about 1
wt. % to less than or equal to about 6 wt. %, optionally greater
than or equal to about 1 wt. % to less than or equal to about 5 wt.
%, or optionally greater than or equal to about 1 wt. % to less
than or equal to about 3 wt. % of the total weight of the
electrode.
[0072] In certain variations, the negative electrode 22 includes
the electrically-conductive material at less than or equal to about
20 wt. %, optionally less than or equal to about 15 wt. %,
optionally less than or equal to about 10 wt. %, optionally less
than or equal to about 5 wt. %, optionally less than or equal to
about 1 wt. %, or optionally greater than or equal to about 0.5 wt.
% to less than or equal to about 8 wt. % of the total weight of the
negative electrode. While the electrically conductive materials may
be described as powders, these materials can lose their powder-like
character following incorporation into the electrode, where the
associated particles of the supplemental electrically conductive
materials become a component of the resulting electrode
structure.
[0073] The negative electrode current collector 32 may be formed
from copper (Cu) or any other appropriate electrically conductive
material known to those of skill in the art.
[0074] The positive electrode 24 may be formed from a lithium-based
active material that comprises a transition metal and that can
sufficiently undergo lithium intercalation and deintercalation, or
alloying and dealloying, while functioning as the positive terminal
of the battery 20.
[0075] In various aspects, the positive electrode 24 may be one of
a layered-oxide cathode, a spinel cathode, and a polyanion cathode.
For example, layered-oxide cathodes (e.g., rock salt layered
oxides) comprise one or more lithium-based positive electroactive
materials selected from LiNi.sub.xMn.sub.yCo.sub.1-x-yO.sub.2
(where 0.ltoreq.x.ltoreq.1 and 0.ltoreq.y.ltoreq.1),
LiNi.sub.xMn.sub.1-xO.sub.2 (where 0.ltoreq.x.ltoreq.1),
Li.sub.1+xMO.sub.2 (where M is one of Mn, Ni, Co, and Al and
0.ltoreq.x.ltoreq.1) (for example LiCoO.sub.2 (LCO), LiNiO.sub.2,
LiMnO.sub.2, LiNi.sub.0.5Mn.sub.0.5O.sub.2, NMC111, NMC523, NMC622,
NMC 721, NMC811, NCA). Spinel cathodes comprise one or more
lithium-based positive electroactive materials selected from
LiMn.sub.2O.sub.4 and LiNi.sub.0.5Mn.sub.1.5O.sub.4. Olivine type
cathodes comprise one or more lithium-based positive electroactive
materials such as LiV.sub.2(PO.sub.4).sub.3, LiFePO.sub.4,
LiCoPO.sub.4, and LiMnPO.sub.4. Tavorite type cathodes comprise,
for example, LiVPO.sub.4F. Borate type cathodes comprise, for
example, one or more of LiFeBO.sub.3, LiCoBO.sub.3, and
LiMnBO.sub.3. Silicate type cathodes comprise, for example,
Li.sub.2FeSiO.sub.4, Li.sub.2MnSiO.sub.4, and LiMnSiO.sub.4F. In
still further variations, the positive electrode 24 may comprise
one or more other positive electroactive materials, such as one or
more of dilithium (2,5-dilithiooxy)terephthalate and polyimide. In
various aspects, the positive electroactive material may be
optionally coated (for example by LiNbO.sub.3 and/or
Al.sub.2O.sub.3) and/or may be doped (for example by one or more of
magnesium (Mg), aluminum (Al), and manganese (Mn)).
[0076] The positive electrode active materials may be powder
compositions. The positive electrode active materials may be
intermingled with an optional electrically conductive material
(e.g., electrically conductive particles) and a polymeric binder.
The binder may both hold together the positive electrode
electroactive material and provide ionic conductivity to the
positive electrode 24. The polymeric binder may include
polyvinylidene fluoride (PVDF), poly(vinylidene chloride) (PVC),
poly((dichloro-1,4-phenylene)ethylene), carboxymethoxyl cellulose
(CMC), nitrile butadiene rubber (NBR), fluorinated urethanes,
fluorinated epoxides, fluorinated acrylics, copolymers of
halogenated hydrocarbon polymers, epoxides, ethylene propylene
diamine termonomer rubber (EPDM), hexafluoropropylene (HFP),
ethylene acrylic acid copolymer (EAA), ethylene vinyl acetate
copolymer (EVA), EAA/EVA copolymers, PVDF/HFP copolymers,
polyvinylidene fluoride (PVDF), lithium polyacrylate (LiPAA),
sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, or
combinations thereof.
[0077] Electrically conductive materials may include graphite,
other carbon-based materials, conductive metals, or conductive
polymer particles. Carbon-based materials may include, by way of
non-limiting example, particles of KETCHEN.TM. black, DENKA.TM.
black, acetylene black, carbon black, carbon nanotubes, and the
like. Conductive metal particles may include nickel, gold, silver,
copper, aluminum, and the like. Examples of a conductive polymer
include polyaniline, polythiophene, polyacetylene, polypyrrole, and
the like. In certain aspects, mixtures of electrically conductive
materials may be used.
[0078] A positive electrode may comprise the positive electrode
active material present at greater than about 60 wt. % of the
overall weight of the electrode, optionally greater than or equal
to about 65 wt. %, optionally greater than or equal to about 70 wt.
%, optionally greater than or equal to about 75 wt. %, optionally
greater than or equal to about 80 wt. %, optionally greater than or
equal to about 85 wt. %, optionally greater than or equal to about
90 wt. %, and in certain variations, optionally greater than or
equal to about 95% of the overall weight of the electrode.
[0079] The binder may be present in the positive electrode 24 at
greater than or equal to about 1 wt. % to less than or equal to
about 20 wt. %, optionally greater than or equal to about 1 wt. %
to less than or equal to about 15 wt. %, optionally greater than or
equal to about 1 wt. % to less than or equal to about 10 wt. %,
optionally greater than or equal to about 1 wt. % to less than or
equal to about 5 wt. %, or optionally greater than or equal to
about 1 wt. % to less than or equal to about 3 wt. % of the total
weight of the electrode.
[0080] In certain variations, the positive electrode 24 includes
the electrically-conductive material at less than or equal to about
20 wt. %, optionally less than or equal to about 10 wt. %,
optionally less than or equal to about 5 wt. %, optionally less
than or equal to about 3 wt. %, optionally greater than or equal to
about 1 wt. % to less than or equal to about 20 wt. % of the total
weight of the positive electrode, optionally greater than or equal
to about 1 wt. % to less than or equal to about 10 wt. % of the
total weight of the positive electrode, or optionally greater than
or equal to about 0.5 wt. % to less than or equal to about 8 wt. %
of the total weight of the positive electrode. While the
electrically conductive materials may be described as powders,
these materials can lose their powder-like character following
incorporation into the electrode, where the associated particles of
the supplemental electrically conductive materials become a
component of the resulting electrode structure.
[0081] As discussed above, the current technology provides systems
and methods for regulating the operating temperature of
electrochemical cells or batteries, and battery packs including one
or more electrically connected (e.g., in series or parallel)
electrochemical cells or batteries. FIG. 3A illustrates an example
temperature control or regulating element 300 capable of active
heating and passive cooling. The temperature control element 300
comprises one or more first elements or layers or foils 310A, 310B
comprising anisotropic thermal and/or electrically conducting
materials disposed between two or more structural elements or
layers 320A, 320B. For example, as illustrated, the temperature
control element 300 includes two first layers 310A, 310B disposed
(i.e., sandwiched) between a first structural layer 320A and a
second structural layer 320B. In certain instances, although not
illustrated, the temperature control element 300 may further
include additional layers, such as a third structural layer 320C
disposed between the lower first layer 310A and the upper first
layer 310B.
[0082] Anisotropic refers to materials having a physical property
that has different values when measured in different directions.
For example, graphite sheets may be produced to have a much higher
thermal conductivity in the x-y plane than in the z-plane, which
causes heat to spread laterally unlike most metals where heat
spreads in all directions equally. As such, anisotropic thermal
and/or electrical conducting materials may be good thermal
conductors and when an electrical field is applied in one
direction, such a material can become a heater that remains
non-electrically activated based on the directional placement of
the material. The anisotropic thermal and/or electrical conducting
materials may include graphite, graphene, carbon nanotubes (CNT),
crystal materials (such as boron arsenide), one or more cohesive
powders (cohesive powders are particulates that form aggregates or
agglomerates due to attractive forces between particles, which tend
to increase with smaller particle sizes, for example, particles
having an average particle size below 100 .mu.m), and/or other
conductive inert carbons. Examples of suitable cohesive powders
include graphite flakes and/or metal powder that are compressed
together so as to act as an integral, uninterrupted thermal and/or
electrical conductor.
[0083] The skilled artisan will appreciate that such anisotropic
thermal and/or electrical conducting materials may be treated with
one or more known techniques, for example, passivated so as to, for
example, prevent corrosion, changes in thermal/electrical
conductivity, and the like; coated with known materials (such as
silicon, polyethylene terephthalate (PET), etc., and/or known
oxidization layers (i.e., protectant layers)) so as to improve, for
example, physical characteristics, mechanical strength, and the
like and reduce material breakdown overtime resulting from, for
example, thermal cycling; and/or allowed so as to enhance, for
example, various desirable characteristics. Further, the skilled
artisan will appreciate that such anisotropic thermal and/or
electrical conducting materials are not commonly used for
individually/regionally controlled heating elements.
[0084] The one or more first layers 310A, 310B, including the
anisotropic thermal and/or electrical conducting materials, may
each have a thickness greater than or equal to about 1 .mu.m to
less than or equal to about 10,000 .mu.m. The thickness of the one
or more first layers 310A, 310B, including the anisotropic thermal
and/or electrical conducting materials may be selected so as to
provide, for example, desired thermal and electrical conductivity
and/or mechanical strength, as well as to balance preferred weight,
size, and costs. In certain aspects, the one or more first layers
310A, 310B may have the same thickness of certain cell plates (not
shown) so as to minimize the impact on the thickness of the battery
(not shown).
[0085] The skilled artisan will appreciate that, in various
aspects, the one or more first layers 310A, 310B, including the
anisotropic thermally and/or electrically conducting materials, may
also include one or more known additives, such as fillers and/or
binders. For example, the one or more first layers 310A, 310B may
include one or more thermal conductive material additives that tune
resistance of the one or more first layers 310A, 310B so as to
improve, for example, the generation of self-heat. Such thermally
conductive material additives may also improve the
manufacturability of the one or more first layers 310A, 310B. The
one or more thermal conductive material additives may be polymers
and/or polymers combined with metal compounds as composites, for
example only, as provided in the following table:
TABLE-US-00001 TABLE 1 Example Thermally Conductive Material
Additives Thermal Conductivity Company Polymer Brand w(m K).sup.-1
COOLPOLY .RTM. LCP D5506 10 PPS E5101 20 PPS E5108 10 PC E4505 4
Laticonther PPS Lati80/50 10 PA6 Lati62GR/70 15 DSM PA46
Tanyl-TC153 8 PA46 Stanyl-TC551 14 PA46 Stanyl-RC154 -- Albis
PPSGF46 TedurR9519 -- PP66 AlcomTCE10 10 PA6 AlcomTCE10 10 PBT
AlcomTCE10 10 Ticona PPS FortronPPS -- LCP ZeniteLCP -- Sabic PPS
OTF2A 2.2 PPS OTF2B 1.05
Such polymeric materials may be mixed with one or more metal
compounds, such as, for example only, BeO (219 w(mK).sup.-l), MgO
(36 w(mK).sup.-l), Al.sub.2O.sub.3 (30 w(mK).sup.-1), CaO (15
w(mK).sup.-l), NiO (12 w(mK).sup.-l), AlN (320 w(mK).sup.-l),
and/or SiN (270 w(mK).sup.-l.
[0086] The structural layers 320A, 320B are selected based on the
performance requirements for the particular device. For example, if
the temperature control elements 300 are to be intimately pressed
against battery cells, for example, as shown in FIG. 3A, the type
and application of battery cells and pack (e.g., automotive,
military, commercial, low-voltage, high-voltage) and the battery's
sensitivity to, for example, electromagnetic interference (EMI) and
noise introduction, as well as likelihood of crash, crush,
deformation, irradiation, etc., will guide the selection of the
appropriate structural layers 320A, 320B. In various instances, the
structural layers 320A, 320B may provide the temperature control
element 300 with sufficient mechanical strength, bendability, and
electrical isolation. The structural layers 320A, 320B may minimize
or eliminate possible mechanical damage to or of the one or more
first layers 310A, 310B.
[0087] The structural layers 320A, 320B may be formed of a material
that includes mica, asbestos, marble, porcelain, glass, shellac,
resin, rubber, cotton yarn, paper, linen, rayon, and/or plastic. In
various aspects, the structural layers 320A, 320B may further
include, a single or double-sided adhesive(s) that also has
sufficient mechanical strength, bendability, and electrical
isolation. The single or double-sided adhesive(s) may be sprayed,
flowed, deposited, etc. onto one or more exposed surfaces of the
structural layers 320A, 320B. For example, as illustrated in FIG.
3B, one or more first adhesives may be disposed as a first coating
322 on a first surface 324 of the first structural layer 320A; and
one or more second adhesives may be disposed as a second coating
326 on a second surface 328 of the first structural layer 320A. The
single or double-sided adhesive(s) may comprise, for example,
polyethylene terephthalate (PET), polypropylene (PP), polyethylene
(PE), and/or polytetrafluoroethylene (PTFE).
[0088] The temperature control element 300 also includes one or
more tab layers 330A, 330B, 330C that make both electrical (ohmic)
and thermal connection with the one or more first layers 310A,
310B. The tab layers 330A, 330B, 330C include a relatively high
mechanical strength, electrically conductive material, such as
copper, aluminum, nickel, nickel coated copper, stainless steel,
and/or aluminum alloys. The tab layers 330A, 330B, 330C may be
disposed between one or more of the first layers 310A, 310B and/or
between the one or more first layers 310A, 310B and the one or more
structural layers 320A, 320B. Notably, the tabs 330A, 330B, 330C
may or may not be coextensive along a length 340 of the first
layers 310A, 310B, but rather, as shown in FIG. 3A may only be
disposed on terminal ends 302, 304 of the first layers 310A, 310B,
such that a gap 342 is defined in the central region between each
respective tab 330A, 330B, 330C on a single plane. For example, as
illustrated in FIG. 3A, a first tab layer 330A may be disposed
between the first structural layer 320A and the first layer 310A; a
second tab layer 330B may be disposed between the first layer 310A
and the first layer 310B; a third tab layer 330C may be disposed
between the first layer 310B and the second structural layer 320B.
As discussed above, the tab layers 330A, 330B, 330C may extend the
length of and be substantially coextensive with the surface of one
or more first layers 310A, 310B and/or the one or more structural
layers 320A, 320B. In certain other instances, like that shown in
FIG. 3A, each tab layer 330A, 330B, 330C may include a first piece
or subpart 332 and a second piece or subpart 334. As illustrated,
the first piece 332 of each tab layer 330A, 330B, 330C may be
disposed on, for example extend from, a first side 302 of the
temperature control element 330, and the second piece 334 of each
tab layer 330A, 330B, 330C may be disposed on, for example, extend
from, a second side 304 of the temperature control element 330.
[0089] FIG. 4 illustrates another example temperature control
element 400 capable of active heating and passive cooling of an
electrochemical cell. The temperature control element 400 comprises
a first element 410 disposed between two or more structural
elements or layers 420A, 420B. For example, as illustrated, the
first element 410 may be disposed between a first structural layer
420A and a second structural layer 420B.
[0090] The structural layers 420A, 420B provide the temperature
control element 400 with sufficient mechanical strength,
bendability, and electrical isolation. For example, the structural
layers 420A, 420B may include a material, such as mica, asbestos,
marble, porcelain, glass, shellac, resin, rubber, cotton yarn,
paper, linen, rayon, and/or plastic. In certain aspects, as is
appreciated by the skilled artisan, the structural layers 420A,
420B may further include a single or double-sided adhesive that
also has sufficient mechanical strength, bendability, and
electrical isolation. The single or double-sided adhesive
comprises, for example, polyethylene terephthalate (PET),
polypropylene (PP), polyethylene (PE), and/or
polytetrafluoroethylene (PTFE). The structural layers 420A, 420B
provide mechanical strength to the temperature control element 400
and minimize or eliminate possible mechanical damage to or of the
first element 410.
[0091] The first element 410 is formed of a film or foil 412 that
comprises a plurality of folds (e.g., where the film or foil 412
experiences a change in direction of approximately 180.degree.)
that wrap around one or more insulating layers 414. In other words,
the one or more insulating layers 414 are disposed between the
folds of the film 412. The film 412 comprises one or more
anisotropic thermal and/or electrically conducting materials, and
may have a thickness greater than or equal to about 1 .mu.m to less
than or equal to about 10,000 .mu.m. The anisotropic thermal and/or
electrically conducting materials may include graphite, graphene,
carbon nanotubes (CNT), crystal materials (such as boron arsenide),
cohesive powder, and/or other conductive inert carbons. The one or
more insulating layers 414 may include known insulating
materials.
[0092] The temperature control element 400 also includes one or
more tabs 430A, 430B that make both electrical (ohmic) and thermal
connection with the film 412. The tabs 430A, 430B include a
relatively high strength, electrically conductive material like
those described above in the context of tabs 330A, 330B, 330C in
FIG. 3A, such as copper, aluminum, nickel, nickel coated copper,
stainless steel, and/or aluminum alloys. The tabs 430A, 430B may be
disposed between the first element 410 and the one or more
structural layers 420A, 420B. For example, as illustrated in FIG.
4, a first tab 430A may be disposed between the first element 410
and a first structural layer 420A and a second tab 430B may be
disposed between the first element 410 and a second structural
layer 420B.
[0093] FIG. 5 illustrates yet another example temperature control
element 500 that is capable of active heating and passive cooling
when disposed in heat transfer relationship with an electrochemical
cell. The temperature control element 500 includes two or more
independently controlled temperature zones or regions 510A, 510B.
For example, as illustrated, the temperature control element 500
may have a first temperature control element 510A and a second
temperature control element 510B. Each of the temperature zones
510A, 510B, similar to the temperature control element 300
illustrated in FIG. 3A and/or the temperature control element 400
illustrated in FIG. 4, includes one or more first element or layer
comprising anisotropic thermal and/or electrical conducting
materials disposed between two or more structural layers and one or
more tables. Each temperature zone 510A, 510B may also include one
or more insulating layers, for example similar to insulating layers
414 illustrated in FIG. 4.
[0094] Although not illustrated, the skilled artisan will
appreciate that each of the temperature zones 510A, 510B may have a
configuration similar to the temperature control element 300
illustrated in FIG. 3A and/or the temperature control element 400
illustrated in FIG. 4. However, distinct from the configurations of
FIGS. 3A and 4, the temperature control element 500 illustrated in
FIG. 5, includes a plurality of temperature zones 510A, 510B that
may be independently controlled from one another. As illustrated,
the temperature zones 510A, 510B of the plurality may be separated
using an electrically insulating material 520 and enclosed by, or
disposed between, one or more structural elements or layers
530.
[0095] The electrically insulating material 520 may include known
insulating materials, as would be known to those of skill in the
art. The structural layers 530 provide the temperature control
element 500 with sufficient mechanical strength, bendability, and
electrical isolation. For example, the structural elements 520 may
include mica, asbestos, marble, porcelain, glass, shellac, resin,
rubber, cotton yarn, paper, linen, rayon, and/or plastic. In
certain aspects, the structural layers 520 may further include a
single or double-sided adhesive that also has sufficient mechanical
strength, bendability, and electrical isolation. The single or
double-sided adhesive comprises, for example, polyethylene
terephthalate (PET), polypropylene (PP), polyethylene (PE), and/or
polytetrafluoroethylene (PTFE).
[0096] Temperature control elements including an anisotropic
material or element, such as graphite, for example in the form of a
foil, as a heating material or element (e.g., an active heater) and
a cooling material or element (e.g., passive cooling), such as, for
example only, temperature control element 300 illustrated in FIG.
3A and/or temperature control element 400 illustrated in FIG. 4
and/or temperature control element 500 illustrated in FIG. 5, can
be integrated into a battery module and/or battery pack (such as
illustrated in FIG. 2) in various fashions. For example, in certain
instances, as illustrated in FIG. 6, individual temperature control
elements 610 can be disposed between one or more cells 620 within a
battery pack 600. Each cell of the one or more cells 620 may be a
battery 20 such as described in the instance of FIG. 1. Each
temperature control element 610 of the plurality may be a
temperature control element 300 as illustrated in FIG. 3A and/or
temperature control element 400 as illustrated in FIG. 4 and/or
temperature control element 500 as illustrated in FIG. 5. The
asterisks (*) shown in FIG. 6 are meant to illustrate that battery
pack 600 may include any number of alternating cells 620 and
temperature control elements 610.
[0097] As illustrated, each of temperature control elements 610 may
be in electrical communication with, and independently controlled
using, for example, a field-effect transistor and/or pulse width
modulation and/or mechanical connector 612. In this manner, the
temperature control elements 610 may be used to apply different
temperature controls to different regions of the battery pack 600
providing flexible zone control, for example to combat spread from
a runaway cell and to target particular areas within the battery
pack.
[0098] The use of temperature control elements 610 including
anisotropic thermal and/or electrical conducting materials. For
example, graphite may be used, where the resistivity of the
graphite can create an active, even-heating solution to warm the
cells 620 when current is passed through the graphite.
Additionally, the same feature can be used to passively cool the
cells 620 by pulling heat away using the anisotropic nature of the
graphite (e.g., anisotropic thermal conductivities by axis). In
various instances, the joining of the anisotropic element and the
insulating structural element may minimize or prevent thermal
spreading prior to and after heat reaches the insulation so as to
prevent thermal propagation. Further still, the non-combustibility
of the anisotropic thermal and/or electrical conducting materials
provide protection in the instance of cell runaway. For example,
the anisotropic material (e.g., graphite) preferentially spreads
the heat in the x-y plane, and as such, slows the z-plane heat
transfer to adjacent cells so as to reduce peak temperature, thus
mitigating and/or preventing the igniting an adjacent cell. FIG. 6
illustrates one instance including a singular element in which
heat/temperature would be essentially equal at all points in the
solution (assuming the materials, thicknesses, etc. are
homogenous). FIG. 7, as discussed in further detail below, enables
preferential heating by enabling discrete control of different
regions of the battery. For instance, the inner (central) cells
heat and cool differently than the outer (distal) cells.
[0099] As illustrated in FIG. 7, a temperature control element 710
can be wrapped around one or more cells 720 of a battery pack 700.
In other words, the one or more cells 720 are disposed between the
folds of the temperature control element 710. Each cell of the one
or more cells 720 may be a battery 20 such as described in the
context of FIG. 1. Each temperature control element 610 of the
plurality may be a temperature control element 300 illustrated in
FIG. 3A and/or temperature control element 400 illustrated in FIG.
4 and/or temperature control element 500 as illustrated in FIG. 5.
The asterisks (*) as shown in FIG. 7 are meant to illustrate that
battery pack 700 may include any number of alternating cells 720
and temperature control elements 710. As illustrated, the
temperature control element 710 may be in electrical communication
with, and controlled using, for example, a field-effect transistor
and/or pulse width modulation and/or mechanical connector 712.
[0100] Embodiments of the present technology are further
illustrated through the following non-limiting example.
Example
[0101] FIGS. 8A-8B provide cell temperature (.degree. C.) profiles
for example cells over a sixty-minute period.
[0102] FIG. 8A illustrates the temperature profile for a
conventional electrochemical cell (e.g., bare cell), where 830
represents the positive battery terminal, 832 represents the
negative battery terminal, and 834 represents the cell center. In
FIG. 8A, the x-axis 810 represents the test time in minutes, and
the y-axis 820 represents the cell temperature (.degree. C.).
[0103] FIG. 8B illustrates the temperature profile for an
electrochemical cell including a temperature control element in
accordance with various aspects of the present disclosure, where
870 represents the positive battery terminal, 872 represents the
negative battery terminal, and 874 represents the cell center. In
FIG. 8B, the x-axis 850 represents the test time in minutes, and
the y-axis 860 represents the cell temperature (.degree. C.).
[0104] As illustrated in FIG. 8A, the bare cell lasted for less
than one minute and the intra-cell temperatures show that the tab
thermocouple is much hotter than the comparative cell prepared in
accordance with various aspects of the present disclosure, as
illustrated in FIG. 8B. More specifically, as illustrated in FIG.
8B, the electrochemical cell, including the temperature control
element in accordance with various aspects of the present
disclosure, ran for about 20 minutes prior to exceeding the
20.degree. C. temperature delta. Moreover, the intra-cell
temperatures for the positive terminal 870, negative terminal 872,
and cell center 874 are much tighter. The tighter temperatures mean
more even intra-cell and inter-cell wear within the comparative
cell prepared in accordance with various aspects of the present
disclosure, providing as improved performance and, in particular,
improved reliability and safety.
[0105] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not
intended to be exhaustive or to limit the disclosure. Individual
elements or features of a particular embodiment are generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and can be used in a selected embodiment, even if
not specifically shown or described. The same may also be varied in
many ways. Such variations are not to be regarded as a departure
from the disclosure, and all such modifications are intended to be
included within the scope of the disclosure.
* * * * *